@FaresDaraghmeh This is exactly how I feel, especially since exclusive or does not necessarily need the indicator "either" to be exclusive. It seems like an exclusive or only.

@KeziaH19 I don't know how much this helps, but this is different from "making an assumption". This lesson is telling us that assumptions that are not confirmed in an argument will weaken the argument's support. What you mean by making an assumption is assuming something is true without it being stated as such. That advice is still valid, just related to a different context!